Known devices may be helpful in providing in-vivo sensing, such as imaging or pH sensing. Autonomous in-vivo sensing devices, such as swallowable or ingestible capsules or other devices may move through a body lumen, sensing as they move along. An autonomous in-vivo sensing device such as an imaging device may include, for example, an imager for obtaining images from inside a body cavity or lumen, such as the gastrointestinal (GI) tract. The imager may, for example, be associated with an optical system, and optionally a transmitter and an antenna. Some of these devices use a wireless connection to transmit image data.
Different methods for estimating the size of objects imaged in a body lumen exist, for example, as described in PCT publication WO2007/074462 to Horn et al., which is directed to a method of determining the size of objects in a body lumen. Horn et al. teach a method of calculating the size of an object in a body lumen, based on for example a laser beam emitted by an irradiation source in the body lumen. The laser beam creates a spot on the image, and if the spot is located on or near the object of interest in the image, the distance to the object and the object's size may be calculated or estimated. However, in situations wherein the spot is not located near the object of interest, the size calculation may not be accurate.